Welcome to YT! Hope your vet can answer your questions and give your little one a good going over to put your mind at ease. You should be able to enjoy your time with the little guy instead of having that nagging worrying feeling in the back of your mind!
Please don't take this the wrong way, but please please don't weigh your puppy on the produce scales. He could be shedding any number of parasites that you aren't aware of and people do use those. They have scales in the kitchen section that are under $15 and weigh from 1/2lb to around 10lbs.